3D parallel numerical simulation of bedding-containing shale based on CT technology and digital image processing

Abstract

The aim of this study is to investigate the effect of bedding inclination on the tensile strength and damage mechanism of shales. In this paper, we obtained images of shale specimens from the Lower Cambrian Niutitang Formation in the northern part of Guizhou Province by CT scanning, reconstructed 3D numerical models of shale at 0°, 30°, 45°, 60° and 90° bedding inclination angles using RFPA-3D finite element software, and performed direct tensile simulation tests. The test results show that the anisotropic nature of the tensile strength of the shale exhibits significant. The tensile strength reaches a minimum value of 2.97 MPa at θ = 0° and a maximum value of 5.27 MPa at θ = 90°. Shale specimens exhibit two modes of damage under uniaxial tension: a mode of damage by tension along the bedding and a mode of damage by compound tension along the bedding and the shale matrix. The spatial distribution of the acoustic emission points better reflects the macroscopic damage pattern of the specimen, and the acoustic emission counts show a single-peak distribution. The research is an important reference for shale reservoir hydraulic fracture sprouting, extension prediction and recovery enhancement.